Moisture in the cross grain of the timber and moisture in the back touch felt will cause the capstain to vary in hight by about ½ mm. I agree that these are the reasons why the capstan appears to be turned up. It doesn't take much humidity to change the configuration a lot. Wim -----Original Message----- From: Tony Caught <acaught at internode.on.net> To: 'David Lawson' <dlawson at davidlawsonspianos.com.au>; pianotech <pianotech at ptg.org> Sent: Sat, Oct 23, 2010 11:17 pm Subject: Re: [pianotech] Regulation mystery Hi David, I have worked in both Darwin and Alice Springs for over 20 years, Darwin humidity varies from 90% to 18% Alice springs Humidity from (at present) 75% to 5%. These readings are for outside so you have to take into consideration the variations in the buildings that house the pianos. Experience has taught me to regulate according to the present climatic conditions in these two places, thus when the air is dry leave the capstains with a big wink (about 1/3 to ½ mil loose) and when the humidity is high, the capstains should be tight. Clearance only for the jack to return on a slow lift of the key. Your capstain has about 6mm lift and the hammer goes forward about 48mm. Moisture in the cross grain of the timber and moisture in the back touch felt will cause the capstain to vary in hight by about ½ mm. Another reason for Dampp-Chasers in pianos. Regards Tony Caught acaught at internode.on.net From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of David Lawson Sent: Sunday, 24 October 2010 6:33 PM To: pianotech at ptg.org Subject: [pianotech] Regulation mystery I regularly service about twenty pianos at a Conservatorium, both uprights and grands. The uprights are mostly Yamaha U1 models about 15 to twenty years old, with a couple of Kawai KS models also. I regulate the lost motion on these instruments so that the capstan holds the wippen so there is no lost motion, however, it is not holding the hammer off the rest. I have just finished the regular maintenance of these this week, and discovered that all but one had increased the height of the capstans to hold the hammers off the hammerest by about 1/4 inch or 6cm. My first reaction was that someone had been at them, turning up the capstan. However, this is not possible as I am the only tech. who attends to these pianos. So, my question is this: Would the sudden change from drought,(about ten years) to very wet conditions, have brought on this amazing change? I find it difficult to believe that this much change could be brought about by humidity. Let's face it, the metal pin holding the capstan is tight into the rear of the key, which would surely not increase the height by this much with humidity! I checked the back touch on the key-frame, and it seems quite normal.The only piano that did not have this happen to it, had an additional heater in that room, which may give us a clue. Your thoughts please. David Lawson Wangaratta Australia -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20101024/299ad1e6/attachment.htm>
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